How do I calculate soil for a raised bed?

Multiply the inside length by the inside width by the fill depth. Use feet for all three measurements to get cubic feet. Divide cubic feet by 27 to get cubic yards, or convert to liters for bagged soil.

How many bags of soil do I need for a raised garden bed?

Divide the total soil volume by the size of the bag you plan to buy, then round up. This calculator supports common cubic-foot, quart, and liter bag sizes.

Should I fill a raised bed all the way to the top?

Many gardeners leave one or two inches below the rim so water and mulch stay in the bed. Use the fill depth you actually want, not just the height of the boards.

Garden calculator

Raised Bed Soil Calculator

Estimate how much soil you need for a raised garden bed, including cubic feet, cubic yards, liters, bag count, and an optional soil mix breakdown.

Soil needed 32.0 cu ft A 4 ft × 8 ft bed filled 12 in deep.

Bed size

Inside length (feet) Inside width (feet) Fill depth (inches)

Measure the inside dimensions of the bed. If the bed is 12 inches tall but you want room for mulch, enter 10 or 11 inches for fill depth.

Bag and mix options

Bag size Extra settling/waste (%)

Topsoil / base mix (%) Compost (%) Aeration (%)

Mix ratio: 50% topsoil/base mix, 30% compost, 20% aeration.

How to use this raised bed soil calculator

Enter the inside length and width of your raised bed, then enter the depth you plan to fill with soil. The calculator adds your settling allowance and converts the volume into cubic feet, cubic yards, liters, and the number of bags to buy.

For bagged soil, always round up. Soil settles after watering, compost can vary by texture, and it is easier to top off a bed before planting than to run short mid-project.

Common raised bed examples

4 × 8 bed at 12 inches deep: about 32 cubic feet before extra settling allowance.
4 × 4 bed at 10 inches deep: about 13.3 cubic feet before extra settling allowance.
2 × 6 bed at 18 inches deep: about 18 cubic feet before extra settling allowance.

FAQ

What formula does this calculator use?

Soil volume equals length × width × depth. The calculator converts depth from inches to feet, then adds the settling or waste percentage you choose.

What is a good raised bed soil mix?

A common starting point is roughly half topsoil or raised-bed mix, with compost for nutrients and an aeration ingredient such as coarse compost, perlite, pumice, or bark fines. Adjust for your crops and local soil.

Should I order bulk soil or bags?

Bulk soil is often easier for large beds because one cubic yard is 27 cubic feet. Bags are convenient for small beds, balconies, and top-offs, but the bag count can get high quickly.